"Only white people can be racist" is dully wrong.

Everyone can contribute to structures of oppression or institutions of distributed punishment.

In actuality, the people that are mocking this are reversing what they may have heard, that you can't be racist towards white people. Considering the polarisation is fostered by ignorant people on both sides, it's not implausible that the other side then takes this for granted and tries to spin it because it imagines that the other side is mocking it because it heard it from their side first. It's like a game of chinese whispers.

That's not exactly right, either, though. Institutional theory is not directly about individual behaviour, it's (duh) about institutions. Social institutions are, themselves "the principal institutions that make up society" or in more empirical terms, generalised, regular patterns of behaviour, regulated by norms and sanctions, the sanctions themselves being regular patterns of behaviour . So "you can't be racist towards white people" is wrong insofar as it presupposes the phenomenon that is examined is individual behaviour.

So, reviewing, the actual meaning of "you can't be racist to white people" is tautological. Institutions that aren't racist towards white people aren't racist towards white people. Of course you could technically get institutions that are racist towards white people, but that's an empirical concern that has nothing to do with the theoretical framework.

The reason institutional racism and racial prejudice are distinguished is exactly because you otherwise confuse the subject and your description fails. My person can hold racial (or any kind of) prejudice against anyone, but that won't create an institution out of thin air (though it may help form or justify it if other -less idealist- conditions are met). I am willing to participate in a structure, it's just that the structure isn't there and I'm left with the idle willingness. Of course this may lead me to be an asshole, but that's not the same kind of social phenomenon. On the other hand if the institution is in place, my prejudice can be actualised as I can now take part in a structure with real material force. This is sometimes summarised as "racism = prejudice + power", though that is very generic so it doesn't help much if someone only has his preconceptions to go by understanding the theory.

It is to be stressed that all of this is descriptive. Part of the reason ignorant people are confused by this is that they are not capable of strictly delineating descriptive and normative statements in their heads. Noting that existing institutions are not disenfranchising white people and that a black person being a bigot isn't participating in non-existing institutions doesn't mean that it's good or bad, moral or immoral that he's prejudiced. That's not a concern for sociology, it's a concern for normative ethics. Empiric facts may have normative implications but are not themselves normative.

To take a simple practical example. Let's assume we live in a country in a distant planet where there live two groups of people with different hair colours, redheads and blondes. For whatever historical reason color of hair has become part of their social identity, while the redheads happen to generally be in control of economic institutions. In this example we have a lot of blondes that hate redheads and a lot of redheads that hate blondes. At some point, the redheads stop serving blondes in their shops, this is regular behaviour and they may even penalise other redheads (via for example social isolation) for not contributing to this system. The outcome of this is that the access of blondes to economic institutions (that have taken a certain form) is diminished. Practically, this is no different than if the redheads were instead in control of the political institutions and banned the blondes' access. They have no access to the distribution of certain goods with whatever that may entail.

Now let's assume that some blonde somehow managed to start a shop and stops serving redheads. He can't accomplish the same outcome. The redheads, even if they wanted to go to his shop, still have access to the distribution of goods under favorable conditions. His individual action didn't have the institutional backing that would allow him to actually repress the redheads in any meaningful sense.

In one case blondes can't buy stuff, in the other redheads can buy stuff. Of course, you can say that the blonde in the second example is or isn't justified in not serving the redheads, that his action is or isn't the same morally as that of each individual redhead that doesn't serve blondes, but that's a completely different subject. The fact is that his action doesn't have the same social outcome as that of the action of each redhead because the institutional context differs. To say, "yeah but his prejudice makes him a bad person", may or may not be right, but it's not very interesting, either way.

This is obviously a simplistic example, but the point is that there is a clear empirical distinction to be made between individual prejudice and institutional racism and if your theory is blind to it, then your theory has no descriptive power.

Finally, you someone can argue about whether this definition of racism is or isn't better that that, but these are semantics. The important thing is to understand the concepts behind the arbitrary terminology. By this I mean, if you want to say he is "racist", as in "individually racist", and you ascribe to this term the same meaning that I ascribe to "racially prejudiced", then we agree on the substance of the matter and our bickering is about symbolic representation, which is likely arbitrary and can only be discussed in terms of pragmatic utility.

I write this in the service of fostering a higher quality of dialogue, because learns are supposed to be what the subreddit is about and because I'm cool like that.